A solar eclipse is kind of like a field trip to the Sun from Earth. You can see something (with special tinted glasses) that you don't usually see. The sun has a remarkable ring of light around it. This is the corona. If you have a chance to see a solar eclipse, you should do it.

The Outer Layers

The three outer layers of the sun are its atmosphere. The layers are, from inside to outside, the photosphere, the chromosphere, and the corona.

The Photosphere

The
photosphere
is the visible surface of the sun (
Figure
below
). It's the part that we see shining. Surprisingly, the photosphere is also one of the coolest layers of the sun. It is only about 6,000 degrees C.

The sun's atmosphere contains the photosphere, the chromosphere, and the corona. This image was taken by NASA's Spacelab 2 instruments.

The Chromosphere

The
chromosphere
(
Figure
below
) lies above the photosphere. It is about 2,000 km thick. The thin chromosphere is heated by energy from the photosphere. Temperatures range from about 4,000 degrees C to about 10,000 degrees C. The chromosphere is not as hot as other parts of the sun, and it glows red. Jets of gas sometimes fly up through the chromosphere. With speeds up to 72,000 km per hour, the jets can fly as high as 10,000 kilometers.

The chromosphere.

The Corona

The
corona
(
Figure
below
) is the outermost part of the sun's atmosphere. It is the sun’s halo, or “crown.” With a temperature of 1 to 3 million K, the corona is much hotter than the photosphere. The corona extends millions of kilometers into space. Sometime you should try to see a total solar eclipse. If you do, you will see the sun’s corona shining out into space.